Earth and Planetary Sciences › Oceanography

Oceanographic and Atmospheric Processes

Works Count: 88074

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Description

This cluster of papers focuses on oceanic modeling, circulation dynamics, and the impact of various physical processes on the global ocean. It includes studies on tidal analysis, mesoscale eddies, mixed layer depth variations, global heat transport, data assimilation techniques, submesoscale processes, estuarine circulation, and the influence of climate change on ocean dynamics.

Keywords

Oceanic Modeling; Ocean Circulation; Tidal Analysis; Mesoscale Eddies; Mixed Layer Depth; Global Heat Transport; Data Assimilation; Submesoscale Processes; Estuarine Circulation; Climate Change Impact

Improved estimates of global ocean circulation, heat transport and mixing from hydrographic data

2000-11-23

Alexandre Ganachaud , Carl Wunsch

Air-Sea Gas Exchange Rates: Introduction and Synthesis

1986-01-01

Peter S. Liss , Liliane Merlivat

AN OVERVIEW OF THE FUNDAMENTALS OF SEQUENCE STRATIGRAPHY AND KEY DEFINITIONS

1988-01-01

John C. Van Wagoner , Henry W. Posamentier , R. M. Mitchum +4 more

Sea-Level Changes: An Integrated Approach - In October 1985, SEPM sponsored a four-day conference entitled ?Sea-Level Changes ? An Integrated Approach.? The purpose of the conference was to provide a … Sea-Level Changes: An Integrated Approach - In October 1985, SEPM sponsored a four-day conference entitled ?Sea-Level Changes ? An Integrated Approach.? The purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea-level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues. The conference was successful in bringing together scientists from industry, academia, and government, representing all of the major geosciences disciplines. Presentations of many new papers, plus significant releases of data that were previously held proprietary, provided fertile ground for discussion. This much-cited volume represents the best of the material presented at the conference. Includes the early ?Vail? chart.

Upper-level circulation in the South Atlantic Ocean

1991-01-01

Ray Peterson , Lothar Stramma

Global high‐resolution mapping of ocean circulation from TOPEX/Poseidon and ERS‐1 and ‐2

2000-08-15

N. Ducet , Pierre‐Yves Le Traon , Gilles Reverdin

This study focuses on the improved estimation of mesoscale surface ocean circulation obtained by merging TOPEX/Poseidon (T/P) and ERS‐1 and ‐2 altimeter measurements between October 1992 and May 1998. Once … This study focuses on the improved estimation of mesoscale surface ocean circulation obtained by merging TOPEX/Poseidon (T/P) and ERS‐1 and ‐2 altimeter measurements between October 1992 and May 1998. Once carefully intercalibrated and homogenized, these data are merged through an advanced global objective analysis method that allows us to correct for residual long wavelength errors and uses realistic correlation scales of ocean dynamics. The high‐resolution (0.25°×0.25°) merged T/P+ERS‐1 and ‐2 sea level anomaly maps provide more homogeneous and reduced mapping errors than either individual data set and more realistic sea level and geostrophic velocity statistics than T/P data alone. Furthermore, the merged T/P+ERS‐1 and ‐2 maps yield eddy kinetic energy (EKE) levels 30% higher than maps of T/P alone. They also permit realistic global estimates of east and north components of EKE and their seasonal variations, to study EKE sources better. A comparison of velocity statistics with World Ocean Circulation Experiment surface drifters in the North Atlantic shows very good agreement. Comparison with contemporary current meter data in various oceanic regimes also produces comparable levels of energy and similar ratios of northward and eastward energy, showing that the maps are suitable to studying anisotropy. The T/P + ERS zonal and meridional components of the mapped currents usually present comparable rms variability, even though the variability in the Atlantic is more isotropic than that in the Pacific, which exhibits strong zonal changes. The EKE map presents a very detailed description, presumably never before achieved at a global scale. Pronounced seasonal changes of the EKE are found in many regions, notably the northeastern Pacific, the northeastern and northwestern Atlantic, the tropical oceans, and the zonally extended bands centered near 20°S in the Indian and western Pacific Oceans and at 20°N in the northwestern Pacific.

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Ocean forecasting in terrain-following coordinates: Formulation and skill assessment of the Regional Ocean Modeling System

2007-06-30

D. B. Haidvogel , Hernan G. Arango , W. Paul Budgell +7 more

THE DYNAMICS OF LONG WAVES IN A BAROCLINIC WESTERLY CURRENT

1947-10-01

J. G. Charney

Previous studies of the long-wave perturbations of the free atmosphere have been based on mathematical models which either fail to take properly into account the continuous vertical shear in the … Previous studies of the long-wave perturbations of the free atmosphere have been based on mathematical models which either fail to take properly into account the continuous vertical shear in the zonal current or else neglect the variations of the vertical component of the earth's angular velocity. The present treatment attempts to supply both these elements and thereby to lead to a solution more nearly in accord with the observed behavior of the atmosphere. By eliminating from consideration at the outset the meteorologically unimportant acoustic and shearing-gravitational oscillations, the perturbation equations are reduced to a system whose solution is readily obtained. Exact stability criteria are deduced, and it is shown that the instability increases with shear, lapse rate, and latitude, and decreases with wave length. Application of the criteria to the seasonal averages of zonal wind suggests that the westerlies of middle latitudes are a seat of constant dynamic instability. The unstable waves are similar in many respects to the observed perturbations: The speed of propagation is generally toward the east and is approximately equal to the speed of the surface zonal current. The waves exhibit thermal asymmetry and a westward tilt of the wave pattern with height. In the lower troposphere the maximum positive vertical velocities occur between the trough and the nodal line to the east in the pressure field. The distribution of the horizontal mass divergence is calculated, and it is shown that the notion of a fixed level of nondivergence must be replaced by that of a sloping surface of nondivergence. The Rossby formula for the speed of propagation of the barotropic wave is generalized to a baroclinic atmosphere. It is shown that the barotropic formula holds if the constant value used for the zonal wind is that observed in the neighborhood of 600 mb.

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Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE

2002-09-17

Rich Pawlowicz , Bob Beardsley , Steve Lentz

Normal Monthly Wind Stress Over the World Ocean with Error Estimates

1983-07-01

Sol Hellerman , Mel Rosenstein

Over 35 million surface observations covering the world ocean from 1870–1976 have been processed for the purpose of calculating monthly normals and standard errors of the eastward and northward components … Over 35 million surface observations covering the world ocean from 1870–1976 have been processed for the purpose of calculating monthly normals and standard errors of the eastward and northward components of the wind stress and work done by the winds in the lower 10 m of the atmosphere. The fields are intended to serve as boundary conditions for models of the ocean circulation. Wind and air-minus-sea temperatures are calculated in a form suitable for determining stress by any bulk aerodynamics model in which the drag coefficient can be represented by six or less coefficients of a second-degree polynomial in wind speed and stability. The particular case of the wind speed and stability dependent drag coefficient discussed by Bunker is selected for analysis. January and July charts of wind stress, curl of the wind stress, mass transport stream-function, divergence of the Ekman transport and the rate of mechanical energy transfer are illustrated and discussed.

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The “great salinity anomaly” in the Northern North Atlantic 1968–1982

1988-01-01

Robert R. Dickson , Jens Meincke , Svend‐Aage Malmberg +1 more

Climatological Atlas of the World Ocean

1983-12-06

Sydney Levitus

A project to objectively analyze historical ocean temperature, salinity, oxygen, and percent oxygen saturation data for the world ocean has recently been completed at the National Oceanic and Atmospheric Administration's … A project to objectively analyze historical ocean temperature, salinity, oxygen, and percent oxygen saturation data for the world ocean has recently been completed at the National Oceanic and Atmospheric Administration's (NOAA) Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey. The results of the project are being made available through distribution of the Climatological Atlas of the World Ocean (NOAA Professional Paper No. 13), and through distribution of magnetic tapes containing the objective analyses. The sources of data used in the project were the Station Data, Mechanical Bathythermograph, and Expendable Bathythermograph files of the National Oceanographic Data Center (NODC) in Washington, D.C., updated through 1977–1978. The raw data were subjected to quality control procedures, averaged by one‐degree squares, and then used as input to an objective analysis procedure that fills in one‐degree squares containing no data and smooths the results. Due to the lack of synoptic observations for the world ocean, the historical data are composited by annual, seasonal, and (for temperature) monthly periods.

On the meridional extent and fronts of the Antarctic Circumpolar Current

1995-05-01

Alejandro H. Orsi , Thomas Whitworth , Worth D. Nowlin

Abyssal recipes II: energetics of tidal and wind mixing

1998-12-01

Walter Munk , Carl Wunsch

Isopycnal Mixing in Ocean Circulation Models

1990-01-01

Peter R. Gent , James C. McWilliams

A subgrid-scale form for mesoscale eddy mixing on isopycnal surfaces is proposed for use in non-eddy-resolving ocean circulation models. The mixing is applied in isopycnal coordinates to isopycnal layer thickness, … A subgrid-scale form for mesoscale eddy mixing on isopycnal surfaces is proposed for use in non-eddy-resolving ocean circulation models. The mixing is applied in isopycnal coordinates to isopycnal layer thickness, or inverse density gradient, as well as to passive scalars, temperature and salinity. The transformation of these mixing forms to physical coordinates is also presented.

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Open‐ocean convection: Observations, theory, and models

1999-02-01

John Marshall , Friedrich Schott

We review what is known about the convective process in the open ocean, in which the properties of large volumes of water are changed by intermittent, deep‐reaching convection, triggered by … We review what is known about the convective process in the open ocean, in which the properties of large volumes of water are changed by intermittent, deep‐reaching convection, triggered by winter storms. Observational, laboratory, and modeling studies reveal a fascinating and complex interplay of convective and geostrophic scales, the large‐scale circulation of the ocean, and the prevailing meteorology. Two aspects make ocean convection interesting from a theoretical point of view. First, the timescales of the convective process in the ocean are sufficiently long that it may be modified by the Earth's rotation; second, the convective process is localized in space so that vertical buoyancy transfer by upright convection can give way to slantwise transfer by baroclinic instability. Moreover, the convective and geostrophic scales are not very disparate from one another. Detailed observations of the process in the Labrador, Greenland, and Mediterranean Seas are described, which were made possible by new observing technology. When interpreted in terms of underlying dynamics and theory and the context provided by laboratory and numerical experiments of rotating convection, great progress in our description and understanding of the processes at work is being made.

V<scp>ERTICAL</scp> M<scp>IXING</scp>, E<scp>NERGY</scp>, <scp>AND THE</scp> G<scp>ENERAL</scp> C<scp>IRCULATION OF THE</scp> O<scp>CEANS</scp>

2003-04-08

Carl Wunsch

▪ Abstract The coexistence in the deep ocean of a finite, stable stratification, a strong meridional overturning circulation, and mesoscale eddies raises complex questions concerning the circulation energetics. In particular, … ▪ Abstract The coexistence in the deep ocean of a finite, stable stratification, a strong meridional overturning circulation, and mesoscale eddies raises complex questions concerning the circulation energetics. In particular, small-scale mixing processes are necessary to resupply the potential energy removed in the interior by the overturning and eddy-generating process. A number of lines of evidence, none complete, suggest that the oceanic general circulation, far from being a heat engine, is almost wholly governed by the forcing of the wind field and secondarily by deep water tides. In detail however, the budget of mechanical energy input into the ocean is poorly constrained. The now inescapable conclusion that over most of the ocean significant “vertical” mixing is confined to topographically complex boundary areas implies a potentially radically different interior circulation than is possible with uniform mixing. Whether ocean circulation models, either simple box or full numerical ones, neither explicitly accounting for the energy input into the system nor providing for spatial variability in the mixing, have any physical relevance under changed climate conditions is at issue.

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Global observations of nonlinear mesoscale eddies

2011-01-29

Dudley B. Chelton , Michael G. Schlax , R. M. Samelson

Flux of Gases across the Air-Sea Interface

1974-01-01

Peter S. Liss , P. G. Slater

Parameterization of Vertical Mixing in Numerical Models of Tropical Oceans

1981-11-01

R. C. Pacanowski , S. George Philander

Measurements indicate that mixing processes are intense in the surface layers of the ocean but weak below the thermocline, except for the region below the core of the Equatorial Undercurrent … Measurements indicate that mixing processes are intense in the surface layers of the ocean but weak below the thermocline, except for the region below the core of the Equatorial Undercurrent where vertical temperature gradients are small and the shear is large. Parameterization of these mixing processes by means of coefficients of eddy mixing that are Richardson-number dependent, leads to realistic simulations of the response of the equatorial oceans to different windstress patterns. In the case of eastward winds results agree well with measurements in the Indian Ocean. In the case of westward winds it is of paramount importance that the nonzero heat flux into the ocean be taken into account. This beat flux stabilizes the upper layers and reduces the intensity of the mixing, especially in the cast. With an appropriate surface boundary condition, the results are relatively insensitive to values assigned to constants in the parameterization formula.

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Sea-level changes: An integrated approach

1986-01-01

Charles A. Ross , June R. P. Ross

Research Article| June 01, 1986 Sea-level changes: An integrated approach Charles A. Ross; Charles A. Ross 1Chevron U.S.A., Inc., Houston, Texas 77251 Search for other works by this author on: … Research Article| June 01, 1986 Sea-level changes: An integrated approach Charles A. Ross; Charles A. Ross 1Chevron U.S.A., Inc., Houston, Texas 77251 Search for other works by this author on: GSW Google Scholar June R. P. Ross June R. P. Ross 2Western Washington University, Bellingham, Washington 98225 Search for other works by this author on: GSW Google Scholar Author and Article Information Charles A. Ross 1Chevron U.S.A., Inc., Houston, Texas 77251 June R. P. Ross 2Western Washington University, Bellingham, Washington 98225 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1986) 14 (6): 535. https://doi.org/10.1130/0091-7613(1986)14<535:SCAIA>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Charles A. Ross, June R. P. Ross; Sea-level changes: An integrated approach. Geology 1986;; 14 (6): 535. doi: https://doi.org/10.1130/0091-7613(1986)14<535:SCAIA>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract No Abstract Available. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Modelling the global ocean tides: modern insights from FES2004

2006-09-26

Florent Lyard , Fabien Lefèvre , Thierry Letellier +1 more

A technique for objective analysis and design of oceanographic experiments applied to MODE-73

1976-07-01

F. P. Bretherton , Russ E. Davis , C. B. Fandry

A finite‐volume, incompressible Navier Stokes model for studies of the ocean on parallel computers

1997-03-15

John Marshall , Alistair Adcroft , Chris Hill +2 more

The numerical implementation of an ocean model based on the incompressible Navier Stokes equations which is designed for studies of the ocean circulation on horizontal scales less than the depth … The numerical implementation of an ocean model based on the incompressible Navier Stokes equations which is designed for studies of the ocean circulation on horizontal scales less than the depth of the ocean right up to global scale is described. A “pressure correction” method is used which is solved as a Poisson equation for the pressure field with Neumann boundary conditions in a geometry as complicated as that of the ocean basins. A major objective of the study is to make this inversion, and hence nonhydrostatic ocean modeling, efficient on parallel computers. The pressure field is separated into surface, hydrostatic, and nonhydrostatic components. First, as in hydrostatic models, a two‐dimensional problem is inverted for the surface pressure which is then made use of in the three‐dimensional inversion for the nonhydrostatic pressure. Preconditioned conjugate‐gradient iteration is used to invert symmetric elliptic operators in both two and three dimensions. Physically motivated preconditioners are designed which are efficient at reducing computation and minimizing communication between processors. Our method exploits the fact that as the horizontal scale of the motion becomes very much larger than the vertical scale, the motion becomes more and more hydrostatic and the three‐dimensional Poisson operator becomes increasingly anisotropic and dominated by the vertical axis. Accordingly, a preconditioner is used which, in the hydrostatic limit, is an exact integral of the Poisson operator and so leads to a single algorithm that seamlessly moves from nonhydrostatic to hydrostatic limits. Thus in the hydrostatic limit the model is “fast,” competitive with the fastest ocean climate models in use today based on the hydrostatic primitive equations. But as the resolution is increased, the model dynamics asymptote smoothly to the Navier Stokes equations and so can be used to address small‐scale processes. A “finite‐volume” approach is employed to discretize the model in space in which property fluxes are defined normal to faces that delineate the volumes. The method makes possible a novel treatment of the boundary in which cells abutting the bottom or coast may take on irregular shapes and be “shaved” to fit the boundary. The algorithm can conveniently exploit massively parallel computers and suggests a domain decomposition which allocates vertical columns of ocean to each processing unit. The resulting model, which can handle arbitrarily complex geometry, is efficient and scalable and has been mapped on to massively parallel multiprocessors such as the Connection Machine (CM5) using data‐parallel FORTRAN and the Massachusetts Institute of Technology data‐flow machine MONSOON using the implicitly parallel language Id.

Hydrostatic, quasi‐hydrostatic, and nonhydrostatic ocean modeling

1997-03-15

John Marshall , Chris Hill , Lev T. Perelman +1 more

Ocean models based on consistent hydrostatic, quasi‐hydrostatic, and nonhydrostatic equation sets are formulated and discussed. The quasi‐hydrostatic and nonhydrostatic sets are more accurate than the widely used hydrostatic primitive equations. … Ocean models based on consistent hydrostatic, quasi‐hydrostatic, and nonhydrostatic equation sets are formulated and discussed. The quasi‐hydrostatic and nonhydrostatic sets are more accurate than the widely used hydrostatic primitive equations. Quasi‐hydrostatic models relax the precise balance between gravity and pressure gradient forces by including in a consistent manner cosine‐of‐latitude Coriolis terms which are neglected in primitive equation models. Nonhydrostatic models employ the full incompressible Navier Stokes equations; they are required in the study of small‐scale phenomena in the ocean which are not in hydrostatic balance. We outline a solution strategy for the Navier Stokes model on the sphere that performs efficiently across the whole range of scales in the ocean, from the convective scale to the global scale, and so leads to a model of great versatility. In the hydrostatic limit the Navier Stokes model involves no more computational effort than those models which assume strict hydrostatic balance on all scales. The strategy is illustrated in simulations of laboratory experiments in rotating convection on scales of a few centimeters, simulations of convective and baroclinic instability of the mixed layer on the 1‐ to 10‐km scale, and simulations of the global circulation of the ocean.

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Circulation in the Western Mediterranean Sea

1999-04-01

Claude Millot

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The monsoon circulation of the Indian Ocean

2001-01-01

Friedrich Schott , Julian P. McCreary

Estimates of the Local Rate of Vertical Diffusion from Dissipation Measurements

1980-01-01

T. R. Osborn

Scaling of the turbulent energy equation suggests the balance of terms in the ocean is between turbulent production, dissipation and the loss to buoyancy. In this paper two models for … Scaling of the turbulent energy equation suggests the balance of terms in the ocean is between turbulent production, dissipation and the loss to buoyancy. In this paper two models for the source of oceanic turbulence are considered; namely, production by the Reynolds stress working against a time variable mean shear, and the gravitational collapse of Kelvin-Helmholtz instabilities. Both of these shear instabilities are believed to be important in the ocean. Using values for the critical flux Richardson number and the measurements from studies of Kelvin-Helmholtz instabilities, the efficiency of turbulent mixing is shown to be comparable for the two models. Therefore, a general relationship between the dissipation rate and the buoyancy flux due to the small-scale turbulent velocity fluctuations is derived. The result is expressed as an upper bound on the value of the turbulent eddy coefficient for mass Kρ ⩽ 0.2ε/N2. Values of Kρ are calculated from recent oceanic measurements of energy dissipation. Isopycnal advection and doubly diffusive phenomena are not included in the model.

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An oceanic general circulation model framed in hybrid isopycnic-Cartesian coordinates

2002-01-01

Rainer Bleck

Mixed layer depth over the global ocean: An examination of profile data and a profile‐based climatology

2004-12-01

Clément de Boyer Montégut , Gurvan Madec , Albert Fischer +2 more

A new 2° resolution global climatology of the mixed layer depth (MLD) based on individual profiles is constructed. Previous global climatologies have been based on temperature or density‐gridded climatologies. The … A new 2° resolution global climatology of the mixed layer depth (MLD) based on individual profiles is constructed. Previous global climatologies have been based on temperature or density‐gridded climatologies. The criterion selected is a threshold value of temperature or density from a near‐surface value at 10 m depth (Δ T = 0.2°C or Δσ θ = 0.03 kg m −3 ). A validation of the temperature criterion on moored time series data shows that the method is successful at following the base of the mixed layer. In particular, the first spring restratification is better captured than with a more commonly used larger criteria. In addition, we show that for a given 0.2°C criterion, the MLD estimated from averaged profiles results in a shallow bias of 25% compared to the MLD estimated from individual profiles. A new global seasonal estimation of barrier layer thickness is also provided. An interesting result is the prevalence in mid‐ and high‐latitude winter hemispheres of vertically density‐compensated layers, creating an isopycnal but not mixed layer. Consequently, we propose an optimal estimate of MLD based on both temperature and density data. An independent validation of the maximum annual MLD with oxygen data shows that this oxygen estimate may be biased in regions of Ekman pumping or strong biological activity. Significant differences are shown compared to previous climatologies. The timing of the seasonal cycle of the mixed layer is shifted earlier in the year, and the maximum MLD captures finer structures and is shallower. These results are discussed in light of the different approaches and the choice of criterion.

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A Reanalysis of Ocean Climate Using Simple Ocean Data Assimilation (SODA)

2008-08-01

James A. Carton , Benjamin S. Giese

Abstract This paper describes the Simple Ocean Data Assimilation (SODA) reanalysis of ocean climate variability. In the assimilation, a model forecast produced by an ocean general circulation model with an … Abstract This paper describes the Simple Ocean Data Assimilation (SODA) reanalysis of ocean climate variability. In the assimilation, a model forecast produced by an ocean general circulation model with an average resolution of 0.25° × 0.4° × 40 levels is continuously corrected by contemporaneous observations with corrections estimated every 10 days. The basic reanalysis, SODA 1.4.2, spans the 44-yr period from 1958 to 2001, which complements the span of the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis (ERA-40). The observation set for this experiment includes the historical archive of hydrographic profiles supplemented by ship intake measurements, moored hydrographic observations, and remotely sensed SST. A parallel run, SODA 1.4.0, is forced with identical surface boundary conditions, but without data assimilation. The new reanalysis represents a significant improvement over a previously published version of the SODA algorithm. In particular, eddy kinetic energy and sea level variability are much larger than in previous versions and are more similar to estimates from independent observations. One issue addressed in this paper is the relative importance of the model forecast versus the observations for the analysis. The results show that at near-annual frequencies the forecast model has a strong influence, whereas at decadal frequencies the observations become increasingly dominant in the analysis. As a consequence, interannual variability in SODA 1.4.2 closely resembles interannual variability in SODA 1.4.0. However, decadal anomalies of the 0–700-m heat content from SODA 1.4.2 more closely resemble heat content anomalies based on observations.

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A Comprehensive Ocean-Atmosphere Data Set

1987-10-01

Scott D. Woodruff , Ralph J. Slutz , Roy L. Jenne +1 more

Development is described of a Comprehensive Ocean-Atmosphere Data Set (COADS)—the result of a cooperative project to collect global weather observations taken near the ocean's surface since 1854, primarily from merchant … Development is described of a Comprehensive Ocean-Atmosphere Data Set (COADS)—the result of a cooperative project to collect global weather observations taken near the ocean's surface since 1854, primarily from merchant ships, into a compact and easily used data set. As background, a historical overview is given of how archiving of these marine data has evolved from 1854, when systematic recording of shipboard meteorological and oceanographic observations was first established as an international activity. Input data sets used for COADS are described, as well as the processing steps used to pack input data into compact binary formats and to apply quality controls for identification of suspect weather elements and duplicate marine reports. Seventy-million unique marine reports for 1854–1979 were output from initial processing. Further processing is described, which created statistical summaries for each month of each year of the period, using 2° latitude × 2° longitude boxes. Monthly summary products are available giving 14 statistics (such as the median and the mean) for each of eight observed variables (air and sea-surface temperatures, scalar and vector wind, pressure, humidity, and cloudiness), plus 11 derived variables. Examples of known temporal, spatial, and methodological inhomogeneities in marine data, and plans for periodic updates to COADS, including an update through 1986 scheduled for completion by early 1988, are presented.

A dipole mode in the tropical Indian Ocean

1999-09-01

N. H. Saji , B. N. Goswami , P. N. Vinayachandran +1 more

A generic length-scale equation for geophysical turbulence models

2003-03-01

Lars Umlauf , Hans Burchard

A generalization of a class of differential length-scale equations typically used in second-order turbulence models for oceanic flows is suggested. Commonly used models, like the κ-e model and the Mellor-Yamada … A generalization of a class of differential length-scale equations typically used in second-order turbulence models for oceanic flows is suggested. Commonly used models, like the κ-e model and the Mellor-Yamada model, can be recovered as special cases of this generic model, and thus can be rationally compared. In addition, a method is proposed that yields a generalized framework for the calibration of the most frequently used class of differential length-scale equations. The generic model, calibrated with this method, exhibits a greater range of applicability than any of the traditional models. Stratified flows, plane mixing layers, and turbulence introduced by breaking surface waves are considered besides some classical test cases.

Spatial Variability of Turbulent Mixing in the Abyssal Ocean

1997-04-04

Kurt L. Polzin , John M. Toole , James R. Ledwell +1 more

Ocean microstructure data show that turbulent mixing in the deep Brazil Basin of the South Atlantic Ocean is weak at all depths above smooth abyssal plains and the South American … Ocean microstructure data show that turbulent mixing in the deep Brazil Basin of the South Atlantic Ocean is weak at all depths above smooth abyssal plains and the South American Continental Rise. The diapycnal diffusivity there was estimated to be less than or approximately equal to 0.1 x 10(-4) meters squared per second. In contrast, mixing rates are large throughout the water column above the rough Mid-Atlantic Ridge, and the diffusivity deduced for the bottom-most 150 meters exceeds 5 x 10(-4) meters squared per second. Such patterns in vertical mixing imply that abyssal circulations have complex spatial structures that are linked to the underlying bathymetry.

Geographical Variability of the First Baroclinic Rossby Radius of Deformation

1998-03-01

Dudley B. Chelton , Roland A. deSzoeke , Michael G. Schlax +2 more

Global 1° × 1° climatologies of the first baroclinic gravity-wave phase speed c1 and the Rossby radius of deformation λ1 are computed from climatological average temperature and salinity profiles. These … Global 1° × 1° climatologies of the first baroclinic gravity-wave phase speed c1 and the Rossby radius of deformation λ1 are computed from climatological average temperature and salinity profiles. These new atlases are compared with previously published 5° × 5° coarse resolution maps of λ1 for the Northern Hemisphere and the South Atlantic and with a 1° × 1° fine-resolution map of c1 for the tropical Pacific. It is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5%–15% owing to seemingly minor computational errors. Geographical variations in the new high-resolution maps of c1 and λ1 are discussed in terms of a WKB approximation that elucidates the effects of earth rotation, stratification, and water depth on these quantities. It is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c1 and λ1 at any particular location in the World Ocean. This is rationalized from consideration of the WKB approximation.

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Global observations of large oceanic eddies

2007-08-01

Dudley B. Chelton , Michael G. Schlax , R. M. Samelson +1 more

Ten years of sea‐surface height (SSH) fields constructed from the merged TOPEX/Poseidon (T/P) and ERS‐1/2 altimeter datasets are analyzed to investigate mesoscale variability in the global ocean. The higher resolution … Ten years of sea‐surface height (SSH) fields constructed from the merged TOPEX/Poseidon (T/P) and ERS‐1/2 altimeter datasets are analyzed to investigate mesoscale variability in the global ocean. The higher resolution of the merged dataset reveals that more than 50% of the variability over much of the World Ocean is accounted for by eddies with amplitudes of 5–25 cm and diameters of 100–200 km. These eddies propagate nearly due west at approximately the phase speed of nondispersive baroclinic Rossby waves with preferences for slight poleward and equatorward deflection of cyclonic and anticyclonic eddies, respectively. The vast majority of the eddies are found to be nonlinear.

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An Unstructured Grid, Finite-Volume, Three-Dimensional, Primitive Equations Ocean Model: Application to Coastal Ocean and Estuaries

2003-01-01

Changsheng Chen , Hedong Liu , Robert C. Beardsley

An unstructured grid, finite-volume, three-dimensional (3D) primitive equation ocean model has been developed for the study of coastal oceanic and estuarine circulation. The model consists of momentum, continuity, temperature, salinity, … An unstructured grid, finite-volume, three-dimensional (3D) primitive equation ocean model has been developed for the study of coastal oceanic and estuarine circulation. The model consists of momentum, continuity, temperature, salinity, and density equations and is closed physically and mathematically using the Mellor and Yamada level-2.5 turbulent closure submodel. The irregular bottom slope is represented using a σ-coordinate transformation, and the horizontal grids comprise unstructured triangular cells. The finite-volume method (FVM) used in this model combines the advantages of a finite-element method (FEM) for geometric flexibility and a finite-difference method (FDM) for simple discrete computation. Currents, temperature, and salinity in the model are computed in the integral form of the equations, which provides a better representation of the conservative laws for mass, momentum, and heat in the coastal region with complex geometry. The model was applied to the Bohai Sea, a semienclosed coastal ocean, and the Satilla River, a Georgia estuary characterized by numerous tidal creeks and inlets. Compared with the results obtained from the finite-difference model (ECOM-si), the new model produces a better simulation of tidal elevations and residual currents, especially around islands and tidal creeks. Given the same initial distribution of temperature in the Bohai Sea, the FVCOM and ECOM-si models show similar distributions of temperature and stratified tidal rectified flow in the interior region away from the coast and islands, but FVCOM appears to provide a better simulation of temperature and currents around the islands, barriers, and inlets with complex topography.

The regional oceanic modeling system (ROMS): a split-explicit, free-surface, topography-following-coordinate oceanic model

2004-09-28

Alexander F. Shchepetkin , James C. McWilliams

World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010

2012-04-17

Sydney Levitus , John I. Antonov , Timothy P. Boyer +7 more

We provide updated estimates of the change of ocean heat content and the thermosteric component of sea level change of the 0–700 and 0–2000 m layers of the World Ocean … We provide updated estimates of the change of ocean heat content and the thermosteric component of sea level change of the 0–700 and 0–2000 m layers of the World Ocean for 1955–2010. Our estimates are based on historical data not previously available, additional modern data, and bathythermograph data corrected for instrumental biases. We have also used Argo data corrected by the Argo DAC if available and used uncorrected Argo data if no corrections were available at the time we downloaded the Argo data. The heat content of the World Ocean for the 0–2000 m layer increased by 24.0 ± 1.9 × 10 22 J (±2S.E.) corresponding to a rate of 0.39 W m −2 (per unit area of the World Ocean) and a volume mean warming of 0.09°C. This warming corresponds to a rate of 0.27 W m −2 per unit area of earth's surface. The heat content of the World Ocean for the 0–700 m layer increased by 16.7 ± 1.6 × 10 22 J corresponding to a rate of 0.27 W m −2 (per unit area of the World Ocean) and a volume mean warming of 0.18°C. The World Ocean accounts for approximately 93% of the warming of the earth system that has occurred since 1955. The 700–2000 m ocean layer accounted for approximately one‐third of the warming of the 0–2000 m layer of the World Ocean. The thermosteric component of sea level trend was 0.54 ± .05 mm yr −1 for the 0–2000 m layer and 0.41 ± .04 mm yr −1 for the 0–700 m layer of the World Ocean for 1955–2010.

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An analysis of the variation of ocean floor bathymetry and heat flow with age

1977-02-10

B. Parsons , John G. Sclater

Diurnal cycling: Observations and models of the upper ocean response to diurnal heating, cooling, and wind mixing

1986-07-15

James F. Price , Robert A. Weller , Robert Pinkel

Measurements made from R/P Flip using rapid profiling conductivity, temperature, and depth probes and vector‐measuring current meters provide a new and detailed look at the diurnal cycle of the upper … Measurements made from R/P Flip using rapid profiling conductivity, temperature, and depth probes and vector‐measuring current meters provide a new and detailed look at the diurnal cycle of the upper ocean. A diurnal cycle occurs when solar heating warms and stabilizes the upper ocean. This limits the downward penetration of turbulent wind mixing so that air‐sea fluxes of heat and momentum are surface trapped during midday. The central problem is to learn how the trapping depth D T (mean depth value of the diurnal temperature and velocity response) is set by the competing effects of wind mixing and surface heating. In this data set the diurnal range of surface temperature was observed to vary from , with most of the day‐to‐day variability attributable to variations of wind stress τ. Wind mixing causes a pronounced asymmetry of the T s response by limiting the warming phase to only about half of the period that the surface heat flux Q is positive. The associated wind‐driven current, the diurnal jet, has an amplitude of typically , with no obvious dependence upon τ. The diurnal jet accelerates downwind during the morning and midday. It is turned into the wind by the Coriolis force during early evening and is often erased by the following morning. Under the assumption that wind mixing occurs as an adjustment to shear flow stability, a scaling analysis and a numerical model study show that the daily minimum trapping depth goes like τ/ Q 1/2 . It follows that goes like Q 3/2 /τ and that goes like Q 1/2 . These results, as well as the simulated time dependence of the diurnal cycle, are at least roughly consistent with the observations. The observed time‐averaged velocity profile has a spiral shape reminiscent of the classical Ekman spiral. However, its structure is a consequence of diurnal cycling, and its parameter dependence is in some ways just opposite that of the Ekman model; e.g., increased wind stress may cause decreased vertical shear between fixed levels in the upper ocean.

<i>Buoyancy Effects in Fluids</i>

1974-03-01

J. Scott Turner , Edward R. Benton

Share Icon Share Twitter Facebook Reddit LinkedIn Reprints and Permissions Cite Icon Cite Search Site Citation J. S. Turner, Edward R. Benton; Buoyancy Effects in Fluids. Physics Today 1 March … Share Icon Share Twitter Facebook Reddit LinkedIn Reprints and Permissions Cite Icon Cite Search Site Citation J. S. Turner, Edward R. Benton; Buoyancy Effects in Fluids. Physics Today 1 March 1974; 27 (3): 52–53. https://doi.org/10.1063/1.3128495 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentPhysics Today Search Advanced Search

Interocean exchange of thermocline water

1986-04-15

Arnold L. Gordon

Formation of North Atlantic Deep Water (NADW) represents a transfer of upper layer water to abyssal depths at a rate of 15 to 20 × 10 6 m 3 /s. … Formation of North Atlantic Deep Water (NADW) represents a transfer of upper layer water to abyssal depths at a rate of 15 to 20 × 10 6 m 3 /s. NADW spreads throughout the Atlantic Ocean and is exported to the Indian and Pacific Oceans by the Antarctic Circumpolar Current and deep western boundary currents. Naturally, there must be a compensating flow of upper layer water toward the northern North Atlantic to feed NADW production. It is proposed that this return flow is accomplished primarily within the ocean's warm water thermocline layer. In this way the main thermoclines of the ocean are linked as they participate in a thermohaline‐driven global scale circulation cell associated with NADW formation. The path of the return flow of warm water is as follows: Pacific to Indian flow within the Indonesian Seas, advection across the Indian Ocean in the 10°–15°S latitude belt, southward transfer in the Mozambique Channel, entry into the South Atlantic by a branch of the Agulhas Current that does not complete the retroflection pattern, northward advection within the subtropical gyre of the South Atlantic (which on balance with the southward flux of colder North Atlantic Deep Water supports the northward oceanic heat flux characteristic of the South Atlantic), and cross‐equatorial flow into the western North Atlantic. The magnitude of the return flow increases along its path as more NADW is incorporated into the upper layer of the ocean. Additionally, the water mass characteristics of the return flow are gradually altered by regional ocean‐atmosphere interaction and mixing processes. Within the Indonesian seas there is evidence of strong vertical mixing across the thermocline. The cold water route, Pacific to Atlantic transport of Subantarctic water within the Drake Passage, is of secondary importance, amounting to perhaps 25% of the warm water route transport. The continuity or vigor of the warm water route is vulnerable to change not only as the thermohaline forcing in the northern North Atlantic varies but also as the larger‐scale wind‐driven circulation factors vary. The interocean links within the Indonesian seas and at the Agulhas retroflection may be particularly responsive to such variability. Changes in the warm water route continuity may in turn influence formation characteristics of NADW.

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Sequential data assimilation with a nonlinear quasi‐geostrophic model using Monte Carlo methods to forecast error statistics

1994-05-15

Geir Evensen

A new sequential data assimilation method is discussed. It is based on forecasting the error statistics using Monte Carlo methods, a better alternative than solving the traditional and computationally extremely … A new sequential data assimilation method is discussed. It is based on forecasting the error statistics using Monte Carlo methods, a better alternative than solving the traditional and computationally extremely demanding approximate error covariance equation used in the extended Kalman filter. The unbounded error growth found in the extended Kalman filter, which is caused by an overly simplified closure in the error covariance equation, is completely eliminated. Open boundaries can be handled as long as the ocean model is well posed. Well‐known numerical instabilities associated with the error covariance equation are avoided because storage and evolution of the error covariance matrix itself are not needed. The results are also better than what is provided by the extended Kalman filter since there is no closure problem and the quality of the forecast error statistics therefore improves. The method should be feasible also for more sophisticated primitive equation models. The computational load for reasonable accuracy is only a fraction of what is required for the extended Kalman filter and is given by the storage of, say, 100 model states for an ensemble size of 100 and thus CPU requirements of the order of the cost of 100 model integrations. The proposed method can therefore be used with realistic nonlinear ocean models on large domains on existing computers, and it is also well suited for parallel computers and clusters of workstations where each processor integrates a few members of the ensemble.

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Efficient Inverse Modeling of Barotropic Ocean Tides

2002-02-01

G. D. Egbert , S. Erofeeva

Abstract A computationally efficient relocatable system for generalized inverse (GI) modeling of barotropic ocean tides is described. The GI penalty functional is minimized using a representer method, which requires repeated … Abstract A computationally efficient relocatable system for generalized inverse (GI) modeling of barotropic ocean tides is described. The GI penalty functional is minimized using a representer method, which requires repeated solution of the forward and adjoint linearized shallow water equations (SWEs). To make representer computations efficient, the SWEs are solved in the frequency domain by factoring the coefficient matrix for a finite-difference discretization of the second-order wave equation in elevation. Once this matrix is factored representers can be calculated rapidly. By retaining the first-order SWE system (defined in terms of both elevations and currents) in the definition of the discretized GI penalty functional, complete generality in the choice of dynamical error covariances is retained. This allows rational assumptions about errors in the SWE, with soft momentum balance constraints (e.g., to account for inaccurate parameterization of dissipation), but holds mass conservation constraints. Wh...

A Formulation of a Phase-Independent Wave-Activity Flux for Stationary and Migratory Quasigeostrophic Eddies on a Zonally Varying Basic Flow

2001-03-01

Koutarou Takaya , Hisashi Nakamura

A new formulation of an approximate conservation relation of wave-activity pseudomomentum is derived, which is applicable for either stationary or migratory quasigeostrophic (QG) eddies on a zonally varying basic flow. … A new formulation of an approximate conservation relation of wave-activity pseudomomentum is derived, which is applicable for either stationary or migratory quasigeostrophic (QG) eddies on a zonally varying basic flow. The authors utilize a combination of a quantity A that is proportional to wave enstrophy and another quantity E that is proportional to wave energy. Both A and E are approximately related to the wave-activity pseudomomentum. It is shown for QG eddies on a slowly varying, unforced nonzonal flow that a particular linear combination of A and E, namely, M ≡ (A + E)/2, is independent of the wave phase, even if unaveraged, in the limit of a small-amplitude plane wave. In the same limit, a flux of M is also free from an oscillatory component on a scale of one-half wavelength even without any averaging. It is shown that M is conserved under steady, unforced, and nondissipative conditions and the flux of M is parallel to the local three-dimensional group velocity in the WKB limit. The authors’ conservation relation based on a straightforward derivation is a generalization of that for stationary Rossby waves on a zonally uniform basic flow as derived by Plumb and others. A dynamical interpretation is presented for each term of such a phase-independent flux of the authors or Plumb. Terms that consist of eddy heat and momentum fluxes are shown to represent systematic upstream transport of the mean-flow westerly momentum by a propagating wave packet, whereas other terms proportional to eddy streamfunction anomalies are shown to represent an ageostrophic flux of geopotential in the direction of the local group velocity. In such a flux, these two dynamical processes acting most strongly on the node lines and ridge/trough lines of the eddy streamfunction field, respectively, are appropriately combined to eliminate its phase dependency. The authors also derive generalized three-dimensional transformed Eulerian-mean equations with the residual circulation and eddy forcing both expressed in phase-independent forms. The flux may not be particularly suited for evaluating the exact local budget of M, because of several assumptions imposed in the derivation. Nevertheless, these assumptions seem qualitatively valid in the assessment based on observed and simulated data. The wave-activity flux is a useful diagnostic tool for illustrating a“snapshot” of a propagating packet of stationary or migratory QG wave disturbances and thereby for inferring where the packet is emitted and absorbed, as verified in several applications to the data. It may also be useful for routine climate diagnoses in an operational center.

Open Ocean Momentum Flux Measurements in Moderate to Strong Winds

1981-03-01

William G. Large , S. Pond

Measurements of the momentum flux were made by the Reynolds flux and dissipation methods on a deep water stable tower operated by the Bedford Institute of Oceanography, A modified Gill … Measurements of the momentum flux were made by the Reynolds flux and dissipation methods on a deep water stable tower operated by the Bedford Institute of Oceanography, A modified Gill propeller-vane anemometer was used to measure the velocity. Drag coefficients from 196 Reynolds flux measurements agree well with those reported in Smith (1980) based on independent observations at the same site. Based on 192 runs, a comparison of the dissipation and Reynolds flux results shows excellent agreement on average, for wind speeds from 4 to 20 m s−1. The much more extensive dissipation data set (1086 h from the tower and 505 h from the weathership PAPA, CCGS Quadra) was used to investigate the dependence of the drag coefficient on wind speed, fetch and stability. The drag coefficient reduced to 10 m height and neutral conditions (CDN), is independent of stability and fetch (for fetch/height ≳800) but increases with wind speed above 10 m s−1. Some time series of the momentum flux and drag coefficient are shown to demonstrate additional sources of variation in the drag coefficient. CDN is observed to be smaller, on average. during rising winds than during failing winds or after a change in wind direction. Based on our results and many deep water results of others, we obtainwhere U10 is the wind speed at a height of 10 m. A method for calculating the stress from this CDN and observations of wind speed and surface minus air temperature at heights other than 10 m is also given.

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Improved Extended Reconstruction of SST (1854–1997)

2004-06-01

Thomas M. Smith , Richard W. Reynolds

An improved SST reconstruction for the 1854–1997 period is developed. Compared to the version 1 analysis, in the western tropical Pacific, the tropical Atlantic, and Indian Oceans, more variance is … An improved SST reconstruction for the 1854–1997 period is developed. Compared to the version 1 analysis, in the western tropical Pacific, the tropical Atlantic, and Indian Oceans, more variance is resolved in the new analysis. This improved analysis also uses sea ice concentrations to improve the high-latitude SST analysis and a modified historical bias correction for the 1939–41 period. In addition, the new analysis includes an improved error estimate. Analysis uncertainty is largest in the nineteenth century and during the two world wars due to sparse sampling. The near-global average SST in the new analysis is consistent with the version 1 reconstruction. The 95% confidence uncertainty for the near-global average is 0.4°C or more in the nineteenth century, near 0.2°C for the first half of the twentieth century, and 0.1°C or less after 1950.

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Statistical hydrodynamics

1949-03-01

Lars Onsager

Long-term declining trend of phytoplankton bloom area in the upwelling zone of the northeastern South China Sea under climate variability

2025-06-26

Ying Chen , Hui Zhao | Ocean & Coastal Management

Exact nonlocal hydrodynamics predict rarefaction effects

2025-06-25

NULL AUTHOR_ID | Physical review. E

A global daily mesoscale front dataset from satellite observations: in situ validation and cross-dataset comparison

2025-06-24

Qinwang Xing , Haiqing Yu , Wei Yu +2 more | Earth system science data

Abstract. Ocean fronts have garnered significant attention from researchers across various scientific disciplines due to their profound ecological and climatic impacts. The development of front detection algorithms has enabled the … Abstract. Ocean fronts have garnered significant attention from researchers across various scientific disciplines due to their profound ecological and climatic impacts. The development of front detection algorithms has enabled the automatic extraction of frontal information from satellite observations, providing valuable tools for understanding the biophysical interactions within marine ecosystems. However, the lack of comprehensive validation and comparison of cross-satellite products against in situ observations, along with limited accessibility to frontal datasets, must be addressed to enable the broader application of front detection algorithms. This study promoted the improved histogram-based front detection algorithm to global oceans with additional enhancements, generating the first publicly available, high-resolution, daily global mesoscale front dataset spanning from 1982 to 2023 (Xing et al., 2024a, https://doi.org/10.5281/zenodo.14373832). Global validation using in situ underway observations shows that most in situ and satellite-detected fronts can be matched with each other, with high temporal and spatial consistency, demonstrating the dataset's acceptable performance in detecting fronts. Cross-dataset comparisons reveal that multi-satellite blended products offer the best front detection performance, followed by observation-assimilated ocean model products, while single-satellite and purely simulated products show the lowest performance. In addition, in situ observations show a strong spatial resemblance to global frontal frequency, providing independent validation of the satellite-based global frontal occurrence map. These results enhance confidence in the application of satellite-based front detection, and our global front dataset and detection algorithm may be valuable for both regional and global studies in marine ecology, fisheries, ocean dynamics, and climate change.

Retrieval of Internal Solitary Wave Parameters and Analysis of Their Spatial Variability in the Northern South China Sea Based on Continuous Satellite Imagery

2025-06-24

Kexiao Lu , Tao Xu , Cun Jia +2 more | Remote Sensing

The remote sensing inversion of internal solitary waves (ISWs) enables the retrieval of ISW parameters and facilitates the analysis of their spatial variability. In this study, we utilize continuous optical … The remote sensing inversion of internal solitary waves (ISWs) enables the retrieval of ISW parameters and facilitates the analysis of their spatial variability. In this study, we utilize continuous optical imagery from the FY-4B satellite to extract real-time ISW propagation speeds throughout their evolution from generation to shoaling. ISW parameters are retrieved in the northern South China Sea based on the quantitative relationship between sea surface current divergence and ISW surface features in optical imagery. The inversion method employs a fully nonlinear equation with continuous stratification to account for the strongly nonlinear nature of ISWs and uses the propagation speed extracted from continuous imagery as a constraint to determine a unique solution. The results show that as ISWs propagate from deep to shallow waters in the northern South China Sea, their statistically averaged amplitude initially increases and then decreases, while their propagation speed continuously decreases with decreasing depth. The inversion results are consistent with previous in situ observations. Furthermore, a three-day consecutive remote sensing tracking analysis of the same ISW revealed that the spatial variation in its parameters aligned well with the abovementioned statistical results. The findings provide an effective inversion approach and supporting datasets for extensive ISW monitoring.

Global Observational Estimates of Mesoscale Eddy‐Driven Quasi‐Stokes Velocity and Buoyancy Diffusivity

2025-06-23

Niek Kusters , Dhruv Balwada , Sjoerd Groeskamp | Geophysical Research Letters

Abstract Mesoscale eddies are a dominant reservoir of kinetic energy in the ocean and play an important role in the transport and stirring of tracers such as heat and carbon. … Abstract Mesoscale eddies are a dominant reservoir of kinetic energy in the ocean and play an important role in the transport and stirring of tracers such as heat and carbon. These effects need to be parameterized in most ocean models. A number of studies have observationally quantified eddy effects, but most of these have focused on the diffusivity of passive tracers (Solomon‐Redi diffusivity). However, passive tracer diffusivity is not directly informative about the quasi‐Stokes transport, since this requires estimates of the buoyancy diffusivity (also known as the Gent‐McWilliams diffusivity). Here we obtain the first global observational estimates of the quasi‐Stokes transport, assuming that mesoscale eddies diffuse potential vorticity (PV) rather than buoyancy. These are also used to estimate the corresponding buoyancy diffusivity, which is what is needed in coarse‐resolution ocean models employing the Gent‐McWilliams parameterization. These observational estimates may be used as constraints for future development and tuning of mesoscale parameterizations.

Detection and Driving Factor Analysis of Hypoxia in River Estuarine Zones by Entropy Methods

2025-06-23

Tianrui Pang , Xiaoyu Zhang , Ye Xiong +4 more | Water

Hypoxia in river estuaries poses significant ecological and water safety risks, yet long-term high-frequency monitoring data for comprehensive analysis remain scarce. This study investigates hypoxia dynamics in the Shenzhen River … Hypoxia in river estuaries poses significant ecological and water safety risks, yet long-term high-frequency monitoring data for comprehensive analysis remain scarce. This study investigates hypoxia dynamics in the Shenzhen River Estuary (southern China) using two-year high-frequency monitoring data. A hybrid anomaly detection method integrating wavelet analysis and temporal information entropy was developed to identify hypoxia events. The drivers of hypoxia were also identified with correlation coefficients and transfer entropy (TE). The results reveal frequent spring–summer hypoxia. Turbidity and total nitrogen (TN) exhibited significant negative correlations and time-lagged effects on dissolved oxygen (DO), where TE reaches a peak of 0.05 with lags of 36 and 72 h, respectively. Wastewater treatment plant (WWTP) loads, particularly suspended solids (SSs), showed a linear negative correlation with estuarine DO. Notably, the 2022 data showed minimal correlations (except SSs) due to high baseline pollution, whereas the post-remediation 2023 data revealed stronger linear linkages (especially r = −0.81 for SSs). The proposed “high-frequency localization–low-frequency assessment” detection method demonstrated robust accuracy in identifying hypoxia events, and mechanistic analysis corroborated the time-lagged pollutant impacts. These findings advance hypoxia identification frameworks and highlight the critical role of Turbidity and SSs in driving estuarine oxygen depletion, offering actionable insights for adaptive water quality management.

Object‐Based Evaluation of Seasonal‐to‐Multiyear Marine Heatwave Predictions

2025-06-23

Joseph Cohen , LuAnne Thompson , Elizabeth Maroon +2 more | Geophysical Research Letters

Abstract Accurate and interpretable marine heatwave (MHW) forecasts allow decision makers and industries to plan for and respond to extreme ocean temperature events. Recent work demonstrates skillful pointwise prediction of … Abstract Accurate and interpretable marine heatwave (MHW) forecasts allow decision makers and industries to plan for and respond to extreme ocean temperature events. Recent work demonstrates skillful pointwise prediction of MHWs. Here, we evaluate a method of detecting and predicting spatially connected MHW objects. We apply object‐based forecast verification to the Community Earth Systems Model Seasonal‐to‐Multiyear Large Ensemble (SMYLE) experiment, a set of initialized hindcasts with 20‐member ensembles of 24‐month simulations initialized quarterly from 1970 to 2019. We demonstrate that SMYLE predicts MHWs that occur near observed MHWs with high skill at long lead times, but with errors in location, area, and intensity that grow with lead time. SMYLE exhibits improved skill in predicting the intensity of MHWs in December and January, and worse skill from August to October. This work illustrates the capacity to forecast connected MHW objects and to quantify the uncertainty in those forecasts with potential applications for future community use.

Coupling ocean currents and waves for seamless cross-scale modeling during Medicane Ianos

2025-06-23

Salvatore Causio , Seimur Shirinov , Iván Federico +4 more | Ocean science

Abstract. This study investigates the effects of a two-way wave–circulation coupled modeling framework during extreme weather events, with a particular focus on Medicane Ianos, one of the most intense cyclones … Abstract. This study investigates the effects of a two-way wave–circulation coupled modeling framework during extreme weather events, with a particular focus on Medicane Ianos, one of the most intense cyclones to have occurred in the Mediterranean Sea. By utilizing a high-resolution unstructured numerical grid, the study explores wave–current interactions in both open-ocean and coastal environments. To this scope, we developed the first external coupler dealing with the SHYFEM-MPI circulation model and the WAVEWATCH III wave model. The interactions considered in this framework include sea-state-dependent momentum flux, radiation stress, Doppler shift, dynamic water depth for waves, and effective wind speed. The study adopts a rigorous validation of the formulations using idealized benchmarks tailored for these specific processes. Afterwards, the modeling framework was employed in real-case simulations of Medicane Ianos. The model is calibrated, and the ocean variables are rigorously validated against in situ and Earth observation (EO) data, including satellite-based measurements. The study found that wave-induced surge components contribute from 10 % to 30 % of the total water level during the storm and that sea-state-dependent momentum flux during a medicane can influence the vertical structure of the ocean up to 100 m. The accuracy of the wave model improves by around 3 % in terms of RMSE when coupled with a circulation model. This study underscores the importance of such coupled models in accurately forecasting medicanes, storm surges, and their impacts, particularly as climate change intensifies extreme events in the Mediterranean Sea.

Oceanic Eddy Kinetic Energy in the Spectral Space Regulated by Mesoscale Air–Sea Heat Exchange in the Kuroshio Extension

2025-06-21

Mingkui Li , Jinzhuo Cai , Haiyuan Yang +2 more | Advances in Atmospheric Sciences

Energetics of eddy-mean flow interactions in the Ross Sea

2025-06-21

Kechen Liu , Chengyan Liu , Zhaomin Wang +7 more | Acta Oceanologica Sinica

Long-term prediction of the Gulf Stream meander using OceanNet: a principled neural-operator-based digital twin

2025-06-20

Michael Gray , Ashesh Chattopadhyay , Tianning Wu +2 more | Ocean science

Abstract. Many meteorological and oceanographic processes throughout the eastern US and western Atlantic Ocean, such as storm tracks and shelf water transport, are influenced by the position and warm sea … Abstract. Many meteorological and oceanographic processes throughout the eastern US and western Atlantic Ocean, such as storm tracks and shelf water transport, are influenced by the position and warm sea surface temperature of the Gulf Stream (GS) – the region's western boundary current. Due to highly nonlinear processes associated with the GS, predicting its meanders and frontal position has been a long-standing challenge within the numerical modeling community. Although the weather and climate modeling communities have begun to turn to data-driven machine learning frameworks to overcome analogous challenges, there has been less exploration of such models in oceanography. Using a new dataset from a high-resolution data-assimilative ocean reanalysis (1993–2022) for the northwestern Atlantic Ocean, OceanNet (a neural-operator-based digital twin for regional oceans) was trained to predict the GS's frontal position over subseasonal to seasonal timescales. Here, we present the architecture of OceanNet and the advantages it holds over other machine learning frameworks explored during development. We also demonstrate that predictions of the GS meander are physically reasonable over at least a 60 d period and remain stable for longer. OceanNet can generate a 120 d forecast of the GS meander within seconds, offering significant computational efficiency.

Water Mass Vertical Mixing in The Sulawesi Sea and Makassar Strait During the Second Transition Monsoon

2025-06-20

Shofia Karima , Nining Sari Ningsih , Anastasia Rita Tisiana +1 more | Earth and Planetary Science

The transformation of water masses along the Indonesian Throughflow (ITF) pathway is evident from the disappearance of Western North Pacific Water (WNPW) south of the Makassar Strait, despite its prior … The transformation of water masses along the Indonesian Throughflow (ITF) pathway is evident from the disappearance of Western North Pacific Water (WNPW) south of the Makassar Strait, despite its prior presence in the Sulawesi Sea. One of the primary mechanisms driving this transformation is vertical mixing. This study investigates the characteristics of vertical mixing along the Sulawesi Sea–Makassar Strait route during the second transition season (September–November), using vertical diffusivity (Kz) as a key indicator. The temperature, density, and current velocity data were obtained from the Transport, Internal Waves, and Mixing in the Indonesian Throughflow Regions (TIMIT) cruise in October 2015. The results show spatial variability of vertical mixing both horizontally and vertically. Horizontally, the strongest vertical mixing was observed in the Makassar Strait (Kz = 8.5 × 10−3 m2 /s and Ri = 2.0−2.2), consistent with values reported for the first transition season but exceeding those typical of the southeast monsoon. Vertically, mixing was most intense in the deep layer (Kz = 9.2 × 10−3 m2/s), followed by the homogeneous layer (Kz = 3.9 × 10−3 m2/s), while the weakest is in the thermocline layer (Kz = 1.2 × 10−3 m2/s). These patterns are influenced by the complex interaction of current dynamics and bathymetric features such as sills. The findings highlight the southern Makassar Strait (Transect 4) as a hotspot of vertical mixing and water mass transformation, playing a critical role in shaping ITF structure and the downstream transport of thermohaline properties.

Maintenance of convectively coupled Kelvin waves: relative importance of internal thermodynamic feedback and external momentum forcing

2025-06-20

Mu‐Ting Chien , Daehyun Kim , Patrick Haertel | EarthArXiv (California Digital Library)

Previous studies suggest that convectively coupled Kelvin waves (KWs) are likely maintained by two distinct processes: (1) the internal thermodynamic feedback between KW diabatic heating and temperature and (2) the … Previous studies suggest that convectively coupled Kelvin waves (KWs) are likely maintained by two distinct processes: (1) the internal thermodynamic feedback between KW diabatic heating and temperature and (2) the external momentum forcing from the midlatitude Rossby waves exerting on KW zonal wind. This study quantifies the relative importance of the two processes on KW maintenance by comparing the growth rates of eddy available potential energy (EAPE) and eddy kinetic energy (EKE) within KWs using satellite and reanalysis data. Results show KWs are maintained primarily by the internal thermodynamic feedback in all regions and seasons, especially over the Indian Ocean, where the mean state sea surface temperature is the highest, and the upper tropospheric westerly is the weakest. Overall, the observed relative importance of the two maintenance processes can serve as a reference for numerical simulations of KWs.

Evaluation of the Sun-Glint Masking Algorithm on OCM-3 Operational Products and Impact of Using Simultaneous Sea Surface Winds Available from Scatterometer Onboard EOS-06 Satellite

2025-06-20

Debojyoti Ganguly , K. N. Babu , Anurag Gupta | Journal of the Indian Society of Remote Sensing

A full-information numerical simulation method for 3D marine MT based on arbitrary Fourier transform

2025-06-20

Shi-kun Dai , Hongjun Tian , Dexiang Zhu +1 more | Physica Scripta

Abstract Abstract There are problems with conventional marine magnetotelluric(MT) numerical simulations, such as large computational requirements, approximate boundary conditions, and difficulty in accurately simulating physical information characterized by three-dimensional(3D) partial … Abstract Abstract There are problems with conventional marine magnetotelluric(MT) numerical simulations, such as large computational requirements, approximate boundary conditions, and difficulty in accurately simulating physical information characterized by three-dimensional(3D) partial differential equations (PDE). Therefore, a novel full-information numerical simulation method for 3D marine MT(HMMT) fields based on an arbitrary Fourier transform(AFFT) scheme is proposed in this paper. The core is based on the true seabed physical model, accurately obtaining the wavenumber spectrum of the electromagnetic field in the spatial-wavenumber domain through AFFT, and then transforming all the spectral information of the electromagnetic field into the spatial domain to obtain the accurate electromagnetic field. The method performs two-dimensional(2D) AFFT along the horizontal direction (-∞, +∞), converting the 3D partial differential equations into one-dimensional(1D) ordinary differential equations with different wave numbers for solving, which has high efficiency and low storage characteristics. The vertical direction is retained as the spatial domain and the wave decomposition is introduced to eliminate the influence of the upper and lower boundaries on the simulation area, and the horizontal mesh corresponding to each depth is arbitrary, which has the advantages of high resolution and flexible meshing, balancing the computational accuracy and efficiency. Each element utilizes the high accuracy solution of the 1D shape function and the high efficiency of the Fourier transform to realize the fast and high accuracy forward simulation. Firstly, a 3D seabed model is designed, and the code is validated by comparing it with the numerical solution of the integral equation method (IE). Secondly, according to the distribution characteristics of the wavenumber spectrum of the anomalies in the Fourier domain, we select the wavenumber sampling method and analyze the computational accuracy and efficiency of the algorithm in this paper. Finally, the combined model is designed to analyze the effect of the boundary on the numerical solutions of the proposed algorithm, standard FFT and Gauss-FFT. The results show that the full-information numerical algorithm based on AFFT does not exhibit truncation effects and can quickly and accurately simulate the physical information represented by 3D partial differential equations.

Spatiotemporal impact of mesoscale eddies on chlorophyll-a concentration in the North Atlantic

2025-06-19

Jinkui Cai , Jialong Sun , Sisi Qin +1 more | Frontiers in Marine Science

Introduction Mesoscale eddies play a crucial role in energy transport and ecological regulation in the North Atlantic Ocean. Methods Based on multi-source datasets, including satellite remote sensing and Argo float … Introduction Mesoscale eddies play a crucial role in energy transport and ecological regulation in the North Atlantic Ocean. Methods Based on multi-source datasets, including satellite remote sensing and Argo float observations from 2009 to 2018, this study employs the Velocity Gradient Detection (VGD) method to identify eddy boundaries and cores, in combination with a spatiotemporal dynamic matching technique, to systematically analyze eddy characteristics and their impacts on chlorophyll-a (Chl-a) concentrations. Results Results show that eddy activity is predominantly concentrated in the Gulf Stream extension region (24°N–48°N, 40°W–60°W). Cyclonic eddies significantly elevate surface Chl-a concentrations (0.6–1.8 mg/m³) through upwelling processes, while anticyclonic eddies induce localized enrichment (15%–25% increase) along their peripheries, exhibiting marked seasonal variability. Vertical analysis reveals that eddy-induced Chl-a anomalies can peak at depths of 50–70 m, effectively enhancing subsurface primary productivity. Overall, eddy-driven Chl-a variations contribute approximately 20% to regional primary production. Discussion These findings highlight the functional importance of mesoscale eddies in regulating phytoplankton biomass and underscore their role in advancing our understanding of the marine carbon cycle under changing climate conditions.

Sensitivity study of energy transfer between mesoscale eddies and wind-induced near-inertial oscillations

2025-06-19

Yu Zhang , Jintao Gu , Shengli Chen +3 more | Ocean science

Abstract. Analyses of current observations and numerical simulations at two moorings in the northern South China Sea reveal the transfer of near-inertial energy between the background currents associated with mesoscale … Abstract. Analyses of current observations and numerical simulations at two moorings in the northern South China Sea reveal the transfer of near-inertial energy between the background currents associated with mesoscale eddies and near-inertial currents (NICs). A series of numerical experiments are conducted to determine important parameters affecting the energy transfer between idealized mesoscale eddies and NICs generated by rotating winds. Speeds of NICs transferred by both cyclonic and anticyclonic mesoscale eddies increase linearly with the wind stress and eddy strength. The transferred NICs in anticyclonic eddies have current amplitudes about 6 times larger than in cyclonic eddies. The translation speed of the mesoscale eddy and the wind rotation frequency also affect the conversion of NICs. The energy transfer rate is elevated with the increase in the positive Okubo–Weiss parameter. A simple theoretical analysis is conducted to verify our findings based on numerical results. Analytical solutions confirm the evident asymmetry of the energy transfer between anticyclonic and cyclonic eddies and quantitatively demonstrate the relationship between the wind stress and the near-inertial energy transferred by mesoscale eddies.

Offshore wave and wind energy development in the Southern Hemisphere will remain optimal between 20°E and 180°E by 2100

2025-06-19

Zhao Xiao-hu , Guohe Huang , Yongping Li +6 more | Communications Earth & Environment

Insights into contrasting ENSO influence on SST variations off Australia’s southeast and west coasts

2025-06-18

Zeya Li , Xuebin Zhang , Neil J. Holbrook | npj Climate and Atmospheric Science

Dynamics and energetics of semidiurnal internal tides in the Weddell-Scotia Confluence

2025-06-18

Wenjia Min , Qun Li , Zhiliang Liu +4 more | Acta Oceanologica Sinica

Strengthening ITF and Weakening AMOC: Time Series Evidence of Trends and Causal Pathways to Agulhas Variability

2025-06-18

Sandy Herho , Katarina Herho , Iwan Anwar +1 more | EarthArXiv (California Digital Library)

Multi-decadal observations of major ocean circulation systems reveal contrasting trends and complex inter-basin connectivity patterns that challenge traditional conceptualizations of global ocean circulation. Using non-parametric trend analysis, multi-method causality testing, … Multi-decadal observations of major ocean circulation systems reveal contrasting trends and complex inter-basin connectivity patterns that challenge traditional conceptualizations of global ocean circulation. Using non-parametric trend analysis, multi-method causality testing, and wavelet coherence techniques, we analyzed volume transport time series spanning 1984--2023 for the Indonesian Throughflow (ITF), Agulhas Current system, and Atlantic Meridional Overturning Circulation (AMOC). The ITF demonstrates statistically significant strengthening, with geostrophic and salinity components increasing by 0.79 and 0.28 Sv decade$^{-1}$, respectively ($p &lt; 0.05$). Conversely, the AMOC exhibits robust weakening of $-1.61$ Sv decade$^{-1}$ ($p &lt; 0.0001$), while Agulhas transport shows no significant long-term trends despite substantial interannual variability. Causality analysis reveals four statistically significant pathways linking ITF components to Agulhas variability with lag times of 0--18 months, supported by consensus across maximum cross-correlation, convergent cross mapping, and transfer entropy methods. However, no direct causal connections emerge between either Indo-Pacific system and the AMOC, indicating regional forcing dominance over global-scale coupling on observable timescales. Wavelet coherence analysis identifies dominant annual-scale coupling (0.87--1.30 years) in ITF-Agulhas relationships, with enhanced coherence during major climate events including the 1997--98 El Ni\~{n}o. These findings suggest that contemporary ocean circulation responds primarily to regional forcing mechanisms---intensified Maritime Continent rainfall driving ITF strengthening and weakened North Atlantic convection controlling AMOC decline---rather than operating as a tightly coupled global conveyor belt. The identified statistical relationships provide critical observational constraints for ocean circulation models and highlight the need for sustained monitoring as anthropogenic forcing continues to reshape ocean gateway dynamics.

Predictability and randomization of surface air temperature chaotic dynamics

2025-06-18

A. Bershadskii | EarthArXiv (California Digital Library)

The surface air temperature daily records at the land-based locations with different climate conditions (from the Arctic to Patagonia) have been studied on the daily to intraseasonal time scales (low-frequency … The surface air temperature daily records at the land-based locations with different climate conditions (from the Arctic to Patagonia) have been studied on the daily to intraseasonal time scales (low-frequency annual and seasonal variations have been removed by subtracting a wavelet regression from the daily records). It is shown that the power spectra of the daily time series exhibit a universal behavior corresponding to distributed chaos dominated by the buoyancy-inertial and buoyancy-diffusive mechanisms. Global average temperature fluctuations (land-based data) and the tropical Pacific sea surface temperature fluctuations (El Nino/La Nina phenomenon) have also been considered in this context. It is shown that the practical smooth predictability for the surface air temperature dynamics is possible at least up to the fundamental (pumping) period of the distributed chaos.

Application of Large-Scale Rotating Platforms in the Study of Complex Oceanic Dynamic Processes

2025-06-18

Xiaojie Lu , Guoqing Han , Yifan Lin +5 more | Journal of Marine Science and Engineering

As the core components of geophysical dynamic system, oceans and atmospheres are dominated by the Coriolis force, which governs complex dynamic phenomena such as internal waves, gravity currents, vortices, and … As the core components of geophysical dynamic system, oceans and atmospheres are dominated by the Coriolis force, which governs complex dynamic phenomena such as internal waves, gravity currents, vortices, and others involving multi-scale spatiotemporal coupling. Due to the limitations of in situ observations, large-scale rotating tanks have emerged as critical experimental platforms for simulating Earth’s rotational effects. This review summarizes recent advancements in rotating tank applications for studying oceanic flow phenomena, including mesoscale eddies, internal waves, Ekman flows, Rossby waves, gravity currents, and bottom boundary layer dynamics. Advanced measurement techniques, such as particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF), have enabled quantitative analyses of internal wave breaking-induced mixing and refined investigations of vortex merging dynamics. The findings demonstrate that large-scale rotating tanks provide a controllable experimental framework for unraveling the physical essence of geophysical fluid motions. Such laboratory experimental endeavors in a rotating tank can be applied to more extensive scientific topics, in which the rotation and stratification play important roles, offering crucial support for climate model parameterization and coupled ocean–land–atmosphere mechanisms.

On the role of barotropic versus baroclinic dynamics in generating a Taylor Cap at Maud Rise, Weddell Sea

2025-06-17

Birte Gülk , Fabien Roquet , David Ferreira +1 more | Journal of Physical Oceanography

Abstract A Taylor Cap originates from the flow’s impingement on a seamount and subsequent formation of a quasi-stagnant volume above it, which isolates water properties and weakens the stratification around … Abstract A Taylor Cap originates from the flow’s impingement on a seamount and subsequent formation of a quasi-stagnant volume above it, which isolates water properties and weakens the stratification around it. Our focus is the Taylor Cap at Maud Rise, Weddell Sea, as this region is prone to open-ocean polynyas. While previous studies have mainly examined the Cap’s formation in a barotropic ocean, little attention has been paid to the role of baroclinic conditions, which are more relevant to the realworld. We study the behavior of a Taylor Cap in response to ambient stratification and inflow conditions in an idealized model set up. Our investigation explores scenarios ranging from a barotropic set up to a simplified, quasi-realistic stratification associated with thermal wind. In the stratified cases, we determine the relative roles of the barotropic (depth-independent) and the baroclinic (depth-dependent) flows, and investigate the local response of stratification. Our results show that the Taylor Cap is primarily generated by the deep barotropic flow, and that the baroclinic component only forms a Taylor Cap if the velocity at the depth of the seamount is sufficiently large. The baroclinic flow is, however, more effective at producing a doming of isopycnals over the seamount. The limited ability of Maud Rise in trapping water masses stems from the Rise’s large fractional height. Lastly, we show that higher inflow velocities lead to a shoaling of isopycnals and reduction of upper-ocean stratification over the seamount, with implications for the potential local onset of deep convection.

Modelling the variability and dynamics of river plumes in Hawke’s Bay, Aotearoa New Zealand

2025-06-17

Charine Collins , Helen Macdonald | Frontiers in Marine Science

A quarter of the freshwater entering the global ocean originates from small rivers, yet the dynamics and environmental impacts of plumes generated by small rivers are understudied. Numerous small rivers … A quarter of the freshwater entering the global ocean originates from small rivers, yet the dynamics and environmental impacts of plumes generated by small rivers are understudied. Numerous small rivers with varying discharge rates terminate in Hawke’s Bay, Aotearoa New Zealand (NZ) delivering large amounts of terrigenous material to the bay. In this study, a realistic, high-resolution hydrodynamic model configuration is used to characterise the river plumes generated in Hawke’s Bay. River plume variability on continental shelves is driven by river discharge, wind forcing and ambient currents which were realistically modelled in this study. A number of rivers terminating in Hawke’s Bay were tagged with a passive tracer which allows for individual plumes to be identified and treated separately and also allows for all plumes to be evaluated simultaneously. The passive tracers were used to investigate the spatio-temporal variability on seasonal and interannual timescales and to identify the main plume patterns and their potential forcing mechanisms. The river plumes generated in Hawke’s Bay are confined to the inner shelf (inshore of the 50 m isobath). Plumes from the numerous small and irregularly spaced rivers coalesce and on occasion a single large plume is generated. Plume coalescence is most often unidirectional, as observed for other systems; however, opposing alongshore currents can occasionally lead to bidirectional coalescence. Two antithetic plume patterns were identified through Self-Organizing Map (SOM) analysis: (i) two small consolidated plumes confined to coastal areas, typical of low discharges and downwelling-favourable winds and (ii) a single, large consolidated plume, typical of high river discharges and upwelling-favourable winds.

Energetically consistent localised APE budgets for local and regional studies of stratified flow energetics

2025-06-17

Rémi Tailleux , Guillaume Roullet | Ocean Modelling

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AdriE: a high-resolution ocean model ensemble for the Adriatic Sea under severe climate change conditions

2025-06-16

Davide Bonaldo , Sandro Carniel , Renato R. Colucci +7 more | Ocean science

Abstract. The Adriatic Sea (eastern Mediterranean Basin) is traditionally considered a natural laboratory for studying a number of oceanographic processes of global interest, including coastal dynamics, dense water formation, and … Abstract. The Adriatic Sea (eastern Mediterranean Basin) is traditionally considered a natural laboratory for studying a number of oceanographic processes of global interest, including coastal dynamics, dense water formation, and thermohaline circulation. More recently, the intensification of the effects of climate change and the increasing awareness of its possible consequences on the natural and socio-economic assets of the Adriatic Basin have opened new research questions and reframed most of the existing ones into a multi-decadal timescale. In this perspective, a description of the possible evolution of the physical oceanographic processes is one of the key requirements for addressing the multi-disciplinary challenges set by climate change, but up to now it has not been possible to combine, for this basin, a sufficiently high resolution in the process description with an estimate of the uncertainty associated with the predictions. This work presents an ensemble modelling approach (AdriE – Adriatic Sea Ensemble) for the kilometre-scale description of hydrodynamics in the Adriatic Sea in an end-of-century time frame. Addressing 3D circulation and thermohaline dynamics within the Regional Ocean Modelling System (ROMS), the ensemble consists of six climate runs encompassing the period from 1987 to 2100 in a severe RCP8.5 scenario forced by the SMHI-RCA4 regional climate model, driven by as many different CMIP5 general climate models made available within the EURO-CORDEX initiative. The climate ensemble is flanked by a dedicated evaluation run for the 1987–2010 period, in which SMHI-RCA4 has been driven by reanalysis fields approximating the best available boundary conditions, thus isolating the intrinsic sources of uncertainty in the RCA4–ROMS modelling chain. In order to allow a direct comparison, the assessment of the model skills in the evaluation run borrows, as far as possible, data and approaches used for the evaluation of a recent kilometre-scale, multi-decadal modelling effort for this region. The model performances are mostly aligned with the state-of-the-art reference. In particular, good results in describing the main features of marine heatwaves and cold spells, such as timing, intensity, and interannual variability, indicate that the AdriE ensemble can effectively be used for studies on the occurrence and effects of thermal extremes in the basin. Future projections suggest an increase in temperature and salinity at upper and intermediate depths, resulting in an overall decrease in water density and possibly in deep ventilation rates. Projected variations are stronger in summer and autumn, and in these seasons the ensemble range is larger than the spatial variability of the quantities and occasionally comparable with the intensity of the climate signal, highlighting the importance of an ensemble approach to treat the climate variability at this timescale. The dataset presented in this study, which can be used for the analysis of coastal and continental margin processes of general interest, is fully available upon request to the corresponding author, and monthly averages of the main quantities are available for each run on a dedicated Zenodo repository.

Fine-scale hydrodynamics around St. John, U.S. Virgin Islands. Part II: variability in residence time in coastal bays

2025-06-16

Yan Jia , Weifeng Zhang , Amy Apprill +1 more | Frontiers in Marine Science

Coastal currents can vary dramatically in space and time, influencing advection and residence time of larvae, nutrients and contaminants in coastal environments. However, spatial and temporal variabilities of the residence … Coastal currents can vary dramatically in space and time, influencing advection and residence time of larvae, nutrients and contaminants in coastal environments. However, spatial and temporal variabilities of the residence time of these materials in coastal environments, such as coastal bays, are rarely quantified in ecological applications. Here, we use a particle tracking model built on top of the high-resolution hydrodynamic model described in Part 1 to simulate the dispersal of particles released in coastal bays around a key and model island study site, St. John, USVI without considering the impact of surface waves. Motivated to provide information for future coral and fish larval dispersal and contaminant spreading studies, this first step of the study toward understanding fine-scale dispersal variability in coastal bays aimed to characterize the cross-bay variability of particle residence time in the bays. Both three-dimensionally distributed (3D) and surface-trapped (surface) particles are considered. Model simulations show pronounced influences of winds, intruding river plumes, and bay orientation on the residence time. The residence times of 3D particles in many of the bays exhibit a clear seasonality, correlating with water column stratification and patterns of the bay-shelf exchange flow. When the water column is well-mixed, the exchange flow is laterally sheared, allowing a significant portion of exported 3D particles to re-enter the bays, resulting in high residence times. During stratified seasons, due to wind forcing or intruding river plumes, the exchange flows are vertically sheared, reducing the chance of 3D particles returning to the bays and their residence time in the bays. For a westward-facing bay with the axis aligned the wind, persistent wind-driven surface flows carry surface particles out of the bays quickly, resulting in a low residence time in the bay; when the bay axis is misaligned with the wind, winds can trap surface particles on the west coast in the bay and dramatically increase their residence time. The strong temporal and inter-bay variation in the duration of particles staying in the bays, and their likely role in larval and contaminant dispersal, highlights the importance of considering fine-scale variability in the coastal circulation when studying coastal ecosystems and managing coastal resources.

Expendable bathythermograph (XBT) data collected along the Southern Ocean chokepoint between Aotearoa / New Zealand and Antarctica, 1994–2024

2025-06-16

Giuseppe Aulicino , Antonino Ian Ferola , Laura Fortunato +7 more | Earth system science data

Abstract. This study presents the water column temperature data collected during several cruises on board the Italica, Araon, and Laura Bassi research vessels in the framework of the Climatic Long-term … Abstract. This study presents the water column temperature data collected during several cruises on board the Italica, Araon, and Laura Bassi research vessels in the framework of the Climatic Long-term Interaction for the Mass balance in Antarctica (CLIMA), Southern Ocean Chokepoints Italian Contribution (SOChIC), and Marine Observatory of the Ross Sea (MORSea) projects funded by the Italian National Antarctic Research Program (PNRA). Data were collected between Aotearoa / New Zealand and the Ross Sea during the austral summers from 1994/1995 to 2023/2024. Across this chokepoint of the Antarctic Circumpolar Current, expendable bathythermograph (XBT) Sippican T7 probes were launched with a regular 20 km sampling, providing temperature profiles with a vertical resolution of 65 cm and a maximum nominal depth of 760 m. All temperature profiles underwent rigorous quality control, including a general malfunctioning verification, the removal of spikes, the consistency check of adjacent profiles, the comparison to regional oceanographic features and satellite altimetry observations, and a final visual check by the operator. Data quality checks led us to discard about 12 % of acquired XBT measurements. The full XBT dataset can be accessed as text format files via the following link: https://doi.org/10.5281/zenodo.14848849 (Aulicino et al., 2025). This dataset contributes to the improvement of our understanding of Southern Ocean features, being highly valuable for studies focusing on climate variability, especially across the Antarctic Circumpolar Current and its fronts. Furthermore, we expect that the collected XBT data will serve as a useful tool for the calibration and validation of recent satellite observations and for the improvement of Southern Ocean oceanographic simulations.

Advances in surface water and ocean topography for fine-scale eddy identification from altimeter sea surface height merging maps in the South China Sea

2025-06-16

Xiaoya Zhang , Lei Liu , Jianfang Fei +6 more | Ocean science

Abstract. The recently launched Surface Water and Ocean Topography (SWOT) satellite mission has reduced the noise levels and increased resolution, thereby improving the ability to detect previously unobserved fine-scale signals. … Abstract. The recently launched Surface Water and Ocean Topography (SWOT) satellite mission has reduced the noise levels and increased resolution, thereby improving the ability to detect previously unobserved fine-scale signals. We employed a method to utilize the unique and advanced abilities of SWOT to validate the accuracy of identified eddies in merged maps of a widely used Archiving, Validation, and Interpretation of Satellite Oceanographic (AVISO) data product and a newly implemented two-dimensional variational method (2DVAR), which uses a 1/12° grid and reduces decorrelation of spatial length scales. SWOT data are more likely to provide detailed comparisons of eddy boundaries for fine-scale to mesoscale structures compared with conventional in situ data (e.g., drifting buoys). The validation results demonstrate that, compared with AVISO, the 2DVAR method exhibited greater consistency with the SWOT observations, especially at small scales, confirming the accuracy and ability of the 2DVAR method in the reconstruction and resolution of fine-scale oceanic dynamical structures.

Observations of coastal wind momentum flux: dependence on fetch and waves with comparisons to COARE

2025-06-16

Yun Chang , Anthony Kirincich , James B. Edson | Journal of Physical Oceanography

Abstract Using observations from the Martha’s Vineyard Coastal Observatory, this paper investigates how momentum flux in the marine atmospheric surface layer over the coastal ocean varies with fetch, wave age … Abstract Using observations from the Martha’s Vineyard Coastal Observatory, this paper investigates how momentum flux in the marine atmospheric surface layer over the coastal ocean varies with fetch, wave age and wave slope, and assesses the performance of the COARE 3.5 bulk parameterization. Long-fetch (at least 300 km) and short-fetch (3-6 km away from land) conditions have very similar momentum flux, with the latter being just 15% higher. The COARE 3.5 wind-speed dependent formulation closely matches the observations. The sea state dependence of wave age and wave slope is analyzed by considering both peak frequency and mean frequency in a wave spectrum. The slope of regression lines between normalized roughness and wave age is sensitive to wind speed ranges and the scatter of momentum flux, potentially explaining why earlier studies did not find an universal formula to characterize the wave dependence. Although the observed momentum flux exhibits an obvious dependence on wave age, a robust quadratic fit between momentum flux and the 10-m neutral wind speed exists only for young waves. For the short-fetch conditions, the momentum flux does not increase as wave slope increases. This may be because waves generated by local wind are still weak and swell that propagates from other areas dominate wave spectra. In other words, wave slope computed by considering the spectra does not properly reflect the local wind-wave interaction.

A Comprehensive Ensemble Model for Marine Atmospheric Boundary-Layer Prediction in Meteorologically Sparse and Complex Regions: A Case Study in the South China Sea

2025-06-13

Yehui Chen , Tao Luo , Gang Sun +5 more | Remote Sensing

Marine atmospheric boundary-layer height (MABLH) is crucial for ocean heat, momentum, and substance transfer, affecting ocean circulation, climate, and ecosystems. Due to the unique geographical location of the South China … Marine atmospheric boundary-layer height (MABLH) is crucial for ocean heat, momentum, and substance transfer, affecting ocean circulation, climate, and ecosystems. Due to the unique geographical location of the South China Sea (SCS), coupled with its complex atmospheric environment and sparse ground-based observation stations, accurately determining the MABLH remains challenging. Coherent Doppler wind lidar (CDWL), as a laser-based active remote sensing technology, provides high-resolution wind profiling by transmitting pulsed laser beams and analyzing backscattered signals from atmospheric aerosols. In this study, we developed a stacking optimal ensemble model (SOEM) to estimate MABLH in the vicinity of the site by integrating CDWL measurements from a representative SCS site with ERA5 (fifth-generation reanalysis dataset from the European Centre for Medium-Range Weather Forecasts) data from December 2019 to May 2021. Based on the categorization of the total cloud cover data into weather conditions such as clear/slightly cloudy, cloudy/transitional, and overcast/rainy, the SOEM demonstrates enhanced performance with an average mean absolute percentage error of 3.7%, significantly lower than the planetary boundary-layer-height products of ERA5. The SOEM outperformed random forest, extreme gradient boosting, and histogram-based gradient boosting models, achieving a robustness coefficient (R2) of 0.95 and the lowest mean absolute error of 32 m under the clear/slightly cloudy condition. The validation conducted in the coastal city of Qingdao further confirmed the superiority of the SOEM in resolving meteorological heterogeneity. The predictions of the SOEM aligned well with CDWL observations during Typhoon Sinlaku (2020), capturing dynamic disturbances in MABLH. Overall, the SOEM provides a precise approach for estimating convective boundary-layer height, supporting marine meteorology, onshore wind power, and coastal protection applications.

Turbulent erosion of a subducting intrusion in the Western Mediterranean Sea

2025-06-13

Giovanni Testa , Mathieu Dever , Mara Freilich +4 more | Ocean science

Abstract. Frontal zones within the Western Alboran Gyre (WAG) are characterized by a density gradient resulting from the convergence of Atlantic and Mediterranean waters. Subduction along isopycnals at the WAG … Abstract. Frontal zones within the Western Alboran Gyre (WAG) are characterized by a density gradient resulting from the convergence of Atlantic and Mediterranean waters. Subduction along isopycnals at the WAG periphery can play a crucial role in upper-ocean ventilation and influences its stratification and biogeochemical cycles. In 2019, physical parameters (comprising temperature, salinity, turbulent kinetic energy dissipation rates) and biogeochemical data (oxygen and chlorophyll a) profiles were collected in transects along the northern edge of the WAG. Several intrusions of subducted water with elevated oxygen, chlorophyll a, and spice anomaly were identified towards the center of the anticyclone. These features had elevated kinetic energy dissipation rates on both their upper and lower boundaries. Analysis of the turbulent fluxes involving heat, salt, oxygen, and chlorophyll a demonstrated a net flux of physical and biogeochemical properties from the intrusions to the surrounding ocean. Either the turbulent or diffusive convection mixing contributed to the observed dilution of the intrusion. Other factors (e.g., water column density stability, variability of the photic layer depth, and organic matter degradation) likely played a role in these dynamics. Enhanced comprehension of the persistence and extent of these features might lead to an improved quantitative parameterization of relevant physical and biogeochemical properties involved in subduction within the study zone.

Using automatic calibration to improve the physics behind complex numerical models: an example from a 3D lake model using Delft3D (v6.02.10) and DYNO-PODS (v1.0)

2025-06-13

Marina Amadori , Abolfazl Irani Rahaghi , Damien Bouffard +1 more | Geoscientific model development

Abstract. Models are simplified descriptions of reality and are intrinsically limited by the assumptions that have been introduced in their formulation. With the development of automatic calibration toolboxes, finding optimal … Abstract. Models are simplified descriptions of reality and are intrinsically limited by the assumptions that have been introduced in their formulation. With the development of automatic calibration toolboxes, finding optimal parameters that suit the environmental system has become more convenient. Here, we explore how optimization toolboxes can be applied innovatively to uncover flaws in the physical formulations of models. We illustrate this approach by evaluating the effect of simplifications embedded in the formulation of a widely used hydro-thermodynamic model. We calibrate a Delft3D model based on temperature profiles for a case study, Lake Morat (Switzerland), through the DYNO-PODS optimization tool. The results show that higher values of the light extinction coefficient can compensate for neglecting the fraction β of short-wave radiation absorbed at the surface of the water. This leads to unrealistic values of the light extinction coefficient, as the optimization pushes its value toward the limit of no transparency, consistent with the need to reproduce a significant absorption at the surface. Although it is well known that β is significantly larger than zero, its absence from the model was never noticed as critical. Automatic calibration tools provide valuable diagnostic insights into the physical robustness of models, enabling more precise evaluation of their structural integrity and performance.

Improving 3D temperature modeling of tropical lakes through seasonal heat flux calibration

2025-06-13

Maurice A. Duka , J. Andrés , Timothy Luis B Bernardo +3 more | Modeling Earth Systems and Environment

A high-frequency dataset of sea level observations from low-cost pressure sensors

2025-06-13

Lucia Pineau‐Guillou , Pascal Lazure | Scientific Data

Vertical structure of mesoscale eddies and their impact on the modulation of tracer fields in the eastern Arabian Sea

2025-06-13

Midhila Varna , A.K. Jithin , P. A. Francis | Journal of Earth System Science

Introduction

2025-06-12

James W. Murray | Oxford University Press eBooks

Abstract Aquatic Geochemical Oceanography is the quantitative study of the geochemistry of the ocean. Chapter 1 introduces the outline of the book, describes why this field is relevant and provides … Abstract Aquatic Geochemical Oceanography is the quantitative study of the geochemistry of the ocean. Chapter 1 introduces the outline of the book, describes why this field is relevant and provides a brief summary of some descriptive oceanography (seafloor topography, major features of ocean margins, major tectonic components and the hypsographic curve of the Earth’s surface). The composition of the ocean and crustal rock types are given followed by a brief history of the field.

Improving coastal water level estimation by merging nadir- only satellite altimetry data into a hydrodynamic model

2025-06-12

Soelem Aafnan Bhuiyan , André de Lima , Tyler Miesse +3 more | Research Square (Research Square)

<title>Abstract</title> Providing robust real time flood warnings to coastal communities is of paramount importance to coastal communities. Although state-of-the-art hydrodynamic models are capable of robustly predicting Coastal Water Levels (CWL), … <title>Abstract</title> Providing robust real time flood warnings to coastal communities is of paramount importance to coastal communities. Although state-of-the-art hydrodynamic models are capable of robustly predicting Coastal Water Levels (CWL), unresolved drivers affecting level fluctuations are often not represented by the model governing equations. This work evaluates a novel method to improve the performance of the ADvanced CIRCulation (ADCIRC) hydrodynamic model by assimilating observations from four nadir-only satellite altimetry missions against a set of National Oceanic and Atmospheric Administration (NOAA) gauge stations located across the entire U.S. East Coast. Two different types of simulations were performed – Open Loop (OL) and Data Assimilation (DA). Five different simulations were performed where four different satellite altimetry observations were assimilated individually and combined with two different scenarios – with and without considering the data quality flags. Results indicate that, despite their limited spatial coverage, merging nadir-only observations into ADCIRC from the newly launched Surface Water and Ocean Topography (SWOT)’s nadir altimeter can improve the model performance at 76% of the gauge locations, whereas Sentinel-6 improves 73% of the total locations, Jason-3 74%, and SARAL 21%. Furthermore, combining observations from SWOT-nadir, Jason-3, and Sentinel-6 can improve the ADCIRC performance at more than 80% of the gauge locations for 107-day simulation. Nadir-only satellite altimetry observations can be useful for improving the model performance even if flagged as “poor quality” near the coast. When the flagged data are disregarded, SWOT can improve ADCIRC at 78%, Sentinel-6 at 73%, Jason-3 at 53%, and SARAL at 21% of the gauge locations. The ability to improve the model simulations highly depends on the availability of a satellite overpass nearby. Therefore, model performance can be further enhanced if satellite observations are available during a storm surge event, stressing the importance of frequent satellite overpasses.

Overview of Ocean Distributions and Circulation

2025-06-12

James W. Murray | Oxford University Press eBooks

Abstract The goal of this chapter is to answer the questions, 1) where does the water go? and 2) why does it go there? The fundamental properties of the ocean … Abstract The goal of this chapter is to answer the questions, 1) where does the water go? and 2) why does it go there? The fundamental properties of the ocean (pressure, temperature, salinity and density) are described and methods to measure these properties are discussed. The superposition of forces (pressure gradient, wind, friction, Coriolis) on the density fields result in transports and currents. Sea surface height varies and the Geostrophic and Sverdrup balances result in patterns of major ocean circulation. Ekman Transport results from wind forcing on the surface of the ocean. Equatorial (ENSO), Southern Ocean, Arctic Ocean, thermocline and abyssal circulations are described. The Ocean Conveyor Belt connects all of the ocean.

Water depth modifies winter circulation in 22 deep Japanese waterbodies

2025-06-12

Ryosuke Katayose , Taku Kadoya , Ayato Kohzu +2 more | Hydrobiologia

Abstract Winter circulation is a key dynamic that sustains the seasonality of freshwater ecosystems in temperate regions. However, it may be delayed or lost due to climate change. The occurrence … Abstract Winter circulation is a key dynamic that sustains the seasonality of freshwater ecosystems in temperate regions. However, it may be delayed or lost due to climate change. The occurrence of water circulation is affected by climate and morphological factors of waterbodies. However, although the occurrence of winter circulation has been found to be controlled by the interplay of climatic and morphologic factors, empirical investigations of this interplay remain limited. Thus, we explored the prevalent role of the interaction between climatic and morphologic factors in the occurrence of winter circulation using up to 37 years of data from 22 deep (maximum depth > 20 m) reservoirs in Japan. We found a negative interaction between seasonal air temperature and water depth, indicating that the effect of the temperature condition of the preceding season declines at deeper water depths. Therefore, in line with previous findings regarding relatively shallow lakes, water depth changes the strength of air temperature effect on the occurrence of winter circulation in deep waterbodies. Furthermore, these results highlight the potential to promote winter circulation through water depth management and the importance of understanding patterns across multiple waterbodies to guide management interventions.

Automatic detection algorithm for internal solitary waves based on response characteristics of Sentinel-3 altimeter data

2025-06-12

Xiaojing Gong , Lina Sun , Hao Zhang +1 more | Journal of Applied Remote Sensing

Internal waves in aquariums with characteristic corners

2025-06-12

Zhenhao Li | Pure and Applied Analysis

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